A manual of fish-culture : based on the methods of the United States Commission of Fish and Fisheries, with chapters on the cultivation of oysters and frogs /

"Extracted from U. S. Fish Commission report for 1897, pages 1 to 340, plates 1 to 62 and I to XVIII."

Avaliação da qualidade da água em piscicultura com sistema de cultivo em tanques-rede no município de Santa Fé do Sul - SP

Pós-graduação em Engenharia Civil - FEIS

Impact of fish cage-culture on the community structure of zooplankton in a tropical reservoir

We investigated the impact of fish cage culture on the zooplankton community structure in a tropical reservoir. We hypothesized that community abundance is greater near cages and increases over time due to the increase in food availability. Samplings were performed near, upstream and downstream from net cages, and before and after net cage installation. The abundance of zooplankton increased 15 days after the experiment was set up, followed by a reduction and finally increased. Rotifer abundance showed significant differences among sites (p<0.05) and sampling periods (p<0.001). Significant differences were also observed in total zooplankton and cladoceran abundance (p<0.001). The spatial and temporal variation of the physical and chemical variables were indirectly correlated with the structure and dynamic of the zooplankton community, as they indicated the primary production in the environment. Our hypothesis was rejected, since the zooplankton was abundant at the reference site. Only rotifers showed higher abundance near cages, due to the influence of food availability. Community dynamics during the experiment was also correlated to food availability. Our results suggest an impact of fish farming on the zooplankton community.

Development of Cell Culture Systems from Selected Species of Fish and Prawns

The present work deals with the development of primary cell culture and diploid cell lines from two fishes, such as Poecilia reticulata and Clarias gariepinus. The greatest difficulty experienced was the avoidance of bacterial and fungi contamination. Three types of cell cultures are commonly developed, primary cell culture, diploid cell lines and heteroploid cell lines. Primary cell culture obtained from the animal tissues that have been cultivated in vitro for the first time. They are characterized by the same chromosome number as parent tissue, cultivated in vitro for the first time, have wide range of virus susceptibility, usually not malignant, six chromatin retarded and do not grow as suspension cultures. Diploid cell lines arise from a primary cell culture at the time of subculturing. Diploid cell lines commercially used in virology are W1-38 (human embryonic lung), W1-26 (human embryonic lung) and HEX (Human embryonic kidney). Heteroploid cell lines have been subcultivated with less than 75% of the cells in the population having a diploid chromosome constitution. Tissue cultures have been extensively used in biomedical research. The main applications are in three areas, Karyological studies, Identification and study of hereditary metabolic disorders and Somatic cell genetics. Other applications are in virology and host-parasite relationships. In this study an attempt was made to preserve the ovarian tissue at low temperature in the presence of cryoprotectants so that the tissue can be retrieved at any time and a cell culture could be developed.

Virulence Potential And Antibiotic Susceptibility Pattern Of Motile Aeromonads Associated With Freshwater Ornamental Fish Culture Systems: A Possible Threat To public Health

Aeromonas spp. are ubiquitous aquatic organisms, associated with multitude of diseases in several species of animals, including fishes and humans. In the present study, water samples from two ornamental fish culture systems were analyzed for the presence of Aeromonas. Nutrient agar was used for Aeromonas isolation, and colonies (60 No) were identified through biochemical characterization. Seven clusters could be generated based on phenotypic characters, analyzed by the programme NTSYSpc, Version 2.02i, and identified as: Aeromonas caviae (33.3%), A. jandaei (38.3%) and A. veronii biovar sobria (28.3%). The strains isolated produced highly active hydrolytic enzymes, haemolytic activity and slime formation in varying proportions. The isolates were also tested for the enterotoxin genes (act, alt and ast), haemolytic toxins (hlyA and aerA), involved in type 3 secretion system (TTSS: ascV, aexT, aopP, aopO, ascF–ascG, and aopH), and glycerophospholipid-cholesterol acyltransferase (gcat). All isolates were found to be associated with at least one virulent gene. Moreover, they were resistant to frequently used antibiotics for human infections. The study demonstrates the pathogenic potential of Aeromonas, associated with ornamental fish culture systems suggesting the emerging threat to public health

Relationship between the price of fish and its quality attributes: a study within a community at the University of São Paulo, Brazil

The aim of this study was to evaluate the associations between the products' market price and attributes related to fish purchase and consumption within a university community in Brazil. A structured questionnaire consisting of a five-point Likert scale was used. It was previously tested and made available to the university community via the Internet. The sample comprised 1966 voluntaries including university students and faculty and staff members. A descriptive analysis of data was performed using Spearman's correlation analysis. The results showed that the majority of the respondents (56%) consume fish at home; some consume fish at restaurants (39%), and 5% at family or friends' houses, reinforcing the idea that variables such as culture and reference groups are fundamental determinants of purchase and consumption behavior. It was identified a significant (p < 0.001) and very strong correlation between the attributes price and nutritional value (r = 0.92); price and availability at the usual places of purchase (r = 0.92); price and packaging (r = 0.92); price and brand name (r = 0.91); and price and of the Federal Inspection stamp (r = 0.91) and a low positive correlation (p < 0.001) between the price variable and the initiative for fish traceability (r = 0.16). This study demonstrated that the price of fish is associated with the quality of the product and the attributes related to it such as packaging, nutritional value, and availability of the product in the market.

Biotechnology and fish culture

Biotechnology can currently be considered of importance in aquaculture. The increase in the production of aquatic organisms over the last two decades through the use of biotechnology indicates that in a few generations biotechnology may overtake conventional techniques, at least for the commercially more valuable species. In the last few years, genetics has contributed greatly to fish culture through the application of the more recent techniques developed in biotechnology and in genetic engineering. At present, the most commonly used methods in fish biotechnology are chromosome manipulation and hormonal treatments, which can be used to produce triploid, tetraploid, haploid, gynogenetic and androgenetic fish. These result in the production of individuals and lineages of sterile, monosex or highly endogamic fish. The use of such strategies in fish culture has as a practical objective the control of precocious sexual maturation in certain species; other uses are the production of larger specimens by control of the reproductive process and the attainment of monosex lines containing only those individuals of greater commercial value. The use of new technologies, such as those involved in gene transfer in many species, can result in modified individuals of great interest to aquaculturists and play important roles in specific programmes of fish production in the near future.

Effect of fish density during transportation on stress and mortality of juvenile Tambaqui Colossoma macropomum

The increased demand for juvenile tambaqui Colossoma macropomum for grow-out ponds and stocking programs in the Amazon state of Brazil has increased the transportation of this species. This study was designed to determine the optimum density of juvenile tambaqui during transportation in closed containers. Fish (51.9 ± 3.3 g and 14.9 ± 0.4 cm) were packed in sealed plastic bags and transported for 10 h at four densities: 78, 156, 234, and 312 kg/m3. After transportation, fish from each density were kept in separate 500-L tanks for 96 h. Mortality, 96-h cumulative mortality, water quality, and blood parameters (hematocrit, plasma cortisol, and glucose) were monitored. Fish mortality after transportation was significantly lower at densities of 78 and 156 kg/m3 than at 234 and 312 kg/m3. Cumulative mortality was significantly lower at a density of 78 kg/m3. Dissolved oxygen after 10 h of transportation remained high at a density of 78 kg/m3, but reached critically low values at all other densities. Ammonia concentration was highest at the lowest density and was lower at higher densities. Carbon dioxide concentration was lowest at the density of 78 kg/m3 but higher in the other treatments. Plasma glucose and cortisol increased significantly immediately after transportation at densities of 156, 234, and 312 kg/m3, returning to control values by 24 h. The best density for juvenile tambaqui during a 10-h transportation haul in a closed container was 78 kg/m3. At this density there was no fish mortality, water quality was kept within acceptable values, and fish were not stressed.

Utilization of fish protein hydrolysate in prepared diets for pacu, Piaractus mesopotamicus, larvae

Growth and survival rates of pacu, Piaractus mesopotamicus, larvae fed prepared diets containing different animal protein sources were evaluated. Four diets with the same level of crude protein (CP) (36%) and calories (4.02 kcal gross energy/g of diet) were fed to the larvae. Diets were formulated to contain one of four protein sources: (1) fish meal (FM), (2) tilapia residue silage (TS), (3) protein hydrolysate from tilapia residue (HT), and (4) eviscerated tilapia residue (HET). Larvae were fed Artemia nauplii for six days, prior to the start of the study, and the prepared diet was supplied from day 7 until the study concluded. Variance analysis showed no significant differences (P > 0.05) for survival rates and larval final lengths among treatments. However, final average weights were significantly different (P < 0.05 for larvae fed FM and HT. Average survival rates were relatively high and ranged from 68.1% to 73.9%. After the live food was replaced by prepared diets, no larval growth was observed for any treatment. Fish protein hydrolysate (HT and HET) and fish silage showed potential to be used as ingredients in the diet of pacu larvae. However, hydrolysate inclusion levels, processing methods to minimize nutrient lixiviation, and the best moment to replace live food with an inert diet (weaning) need further investigation. © 2003 by The Haworth Press, Inc. All rights reserved.

Vitellogenin synthesis in primary cultures of fish liver cells as endpoint for in vitro screening of the (anti)estrogenic activity of chemical substances

Concern over possible adverse effects of endocrine-disrupting compounds on fish has caused the development of appropriate testing methods. In vitro screening assays may provide initial information on endocrine activities of a test compound and thereby may direct and optimize subsequent testing. Induction of vitellogenin (VTG) is used as a biomarker of exposure of fish to estrogen-active substances. Since VTG induction can be measured not only in vivo but also in fish hepatocytes in vitro, the use of VTG induction response in isolated fish liver cells has been suggested as in vitro screen for identifying estrogenic-active substances. The main advantages of the hepatocyte VTG assay are considered its ability to detect effects of estrogenic metabolites, since hepatocytes in vitro remain metabolically competent, and its ability to detect both estrogenic and anti-estrogenic effects. In this article, we critically review the current knowledge on the VTG response of cultured fish hepatocytes to (anti)estrogenic substances. In particular, we discuss the sensitivity, specificity, and variability of the VTG hepatocyte assay. In addition, we review the available data on culture factors influencing basal and induced VTG production, the response to natural and synthetic estrogens as well as to xenoestrogens, the detection of indirect estrogens, and the sources of assay variability. The VTG induction in cultured fish hepatocytes is clearly influenced by culture conditions (medium composition, temperature, etc.) and culture system (hepatocyte monolayers, aggregates, liver slices, etc.). The currently available database on estrogen-mediated VTG induction in cultured teleost hepatocytes is too small to support conclusive statements on whether there exist systematic differences of the VTG response between in vitro culture systems, VTG analytical methods or fish species. The VTG hepatocyte assay detects sensitively natural and synthetic estrogens, whereas the response to xenoestrogens appears to be more variable. The detection of weak estrogens can be critical due to the overshadow with cytotoxic concentrations. Moreover, the VTG hepatocyte assay is able to detect antiestrogens as well as indirect estrogens, i.e substances which require metabolic activation to induce an estrogenic response. Nevertheless, more chemicals need to be analysed to corroborate this statement. It will be necessary to establish standardized protocols to minimize assay variability, and to develop a set of pass-fail criteria as well as cut-offs for designating positive and negative responses.